We have further tested and developed our new tool of using mass conservation constraints as a form of Bayesian regularization in multi-signal sedimentation velocity. We have confirmed by computer simulations and application to experimental data sets that it can significantly aid in the spectral discrimination of components. We have finished the complex implementation of this approach in the software SEDPHAT. Towards the study of polysaccharides and other macromolecules with relatively broad particle size distribution, we have embarked on a collaboration with Dr. Stephen Harding for the development of new sedimentation equilibrium approaches based on the principles of M-star analysis and on the direct global fitting with integral equations representing size distributions. It is increasingly recognized that ultra-weak interactions may play an important role in the high concentrations of the cellular milieu. Therefore, we initiated a study of exploiting the measurement of hydrodynamic interactions to report on weak macromolecular interactions. We have identified experimental model systems, and are studying the theoretical framework of hydroydamic and thermodynamic non-ideality. In order to summarize and disseminate the new tools developed by us and others in the field of analytical ultracentrifugation, we wrote a comprehensive review for Current Protocols in Protein Science, and conducted two workshops to teach advanced analytical ultracentrifugation methodology.